It is known practice to crosslink ethylene-vinyl acetate (EVA) copolymers by placing these copolymers in the presence of free-radical-initiating peroxides such as O,O-tert-butyl-O-(2-ethylhexyl) monoperoxycarbonate.
However, the crosslinking times obtained via such processes are long. This results in a loss of productivity for the industries that transform these elastomers into finished products.
Moreover, it is important, during a process of crosslinking of an ethylene-vinyl acetate (EVA) copolymer, to maintain a good crosslinking density. Specifically, the crosslinking density is an indication of the mechanical properties of the finished product. Thus, if the crosslinking density is too low, the finished product may be characterized by a breaking strength and a tear strength that are too low.
There is thus still a need for a mixture for facilitating crosslinking for crosslinkable compositions of elastomeric polymers such as ethylene-vinyl acetate (EVA) copolymers, in particular for the purpose of rapidly manufacturing finished products based on ethylene-vinyl acetate (EVA) copolymer elastomers, while at the same time maintaining a good crosslinking density. There is also still a need for a process for crosslinking such crosslinkable compositions, which has an improved rate of reaction while at the same time maintaining a good crosslinking density.
The Applicant has now discovered, surprisingly, that by using a particular mixture of peroxides, with a particular content for at least one of these peroxides, it is possible to crosslink ethylene-vinyl acetate (EVA) copolymers rapidly while at the same time maintaining a good crosslinking density.